Abstract

Sharp periodic enhancement of high-harmonic generation synchronized to prepulse-induced cluster vibration is observed. Tenfold enhancement of high-harmonic-generation efficiency is achieved by optimal selection of the prepulse–pump delay. This strong correlation between high-harmonic generation and cluster vibration also provides a new tool for studying the vibrational dynamics of nanometer atomic clusters.

Figures (3)

Spectra of the harmonics in the range of 30–47nm generated by the pump pulse with and without the prepulse. The prepulse energy is 0.5mJ, the pump energy is 4.3mJ, the cluster-jet backing pressure is 200psi, and the delay is 12.0ps.

HHG enhancement factor for the 21st harmonic as a function of prepulse–pump separation for various cluster-jet backing pressures. The prepulse energy is 0.5mJ, and the pump energy is 4.3mJ. The enhancement factor is defined as the ratio of HHG energy between the case with the prepulse and the case without. For viewing clarity the curve for 200psi is shifted upwards by 2
units. The error bars denote the standard error of mean for 10 laser shots. The inset illustrates the shape evolution of a cluster for S20 quadrupole-spheroidal vibration.

HHG enhancement factor for the 21st harmonic as a function of prepulse–pump separation for various prepulse energies. The pump pulse energy is 4.3mJ, and the cluster-jet backing pressure is 200psi. For viewing clarity the curve for 0.5mJ is shifted upwards by 3
units.